Although the wetting of textured surfaces have been theoretically studied, their practical utilization is disproportionately rare, and the lack of reproducible experimental data in the field is conspicuous [de Gennes P. G. et al.: Capillarity and Wetting Phenomena, Springer, Berlin, 2003; Lafuma, A.& Quéré, D.: Nature Materials 2 (2003) 457-60].
Highly hydrophobic surfaces are needed in many important applications, such as in manufacturing water-repellant textile, in constructing fuel cells, in batteries for membranes non-wetted under storage, desalination membranes, antenna coatings, etc. The phenomenon of superhydrophobi-city, i.e. the situation when apparent contact angle (ACA) becomes close to 180°, was reported recently by different groups [Gao, L. & McCarthy T. J.: Langmuir 22 (2006) 2966-7; Vogelaar L. et al.: Langmuir 22 (2006) 3125-30; Bico J. et al.: Colloids and Surfaces A 206 (2002) 41-46]. Various sophisticated techniques, including UV, soft lithography [He B. et al.: Colloids and Surfaces A 248 (2004) 101-4], temperature directed capillary molding [Jeong H. E. et al.: Langmuir 22 (2006) 1640-5], and various materials, including perfluoroacrylates [Lafuma A. & Quéré D.: Nature Materials 2 (2003) 457-60], and alkylketene dimers [Shibuichi A. et al.: J. Phys. Chem. 100 (1996) 19512-7] were applied for manufacturing super water-repellent surfaces. Superhydrophobic surfaces are also found in nature [Herminghaus S.: Europhysics Letters 52 (2000) 165-70; Barthlott W. & Neinhuis C.: Planta 202 (1997) 1-8]. The biological expedience of the phenomenon, called the lotus effect, consists in the possibility of self-cleaning of plant leaves due to the rolling of drops without water spreading on the leaf surface.
Practical needs of hydrophobic surfaces are not satisfied, particularly in cases when the surface should comprise objects made of inherently hydrophilic materials. In spite of significant experimental and theoretical efforts, a reproducible inexpensive manufacture of superhydrophobic surfaces is not available. It is therefore an object of this invention to provide a method of forming a superhydrophobic surface, applicable on a variety of materials. Metallic surfaces are well-known as “high-energy interfaces”, for which the chemical binding is of order of 1 eV, and on which nearly every liquid spreads [de Gennes P. G. et al.: Capillarity and Wetting Phenomena, Springer, Berlin, 2003.] Increasing hydrophobicity on metallic surfaces can be achieved by applying a monolayer of dodecane thiol on textured metallic surfaces [Öner D. & McCarthy T. J.: Langmuir 16 (2000) 7777-82; Yoshimitsu Z. et al.: Langmuir 18 (2002) 5818-22; Abdelsalam M. E. et al.: Langmuir 21 (2005) 1753-7]. However, the applied layer is not always stable, and some applications do not allow applying such layers of chemicals. It is therefore another object of this invention to provide a metal surface possessing hydrophobicity. More generally, another object of the invention is to provide a suitable method of producing hydrophobic surfaces made of relatively hydrophilic materials.
Other objects and advantages of present invention will appear as description proceeds.